Exploitation requires permission to write the tenant's Alertmanager configuration. Grafana Enterprise Metrics (GEM), which is built on Mimir, is also affected. The issue is fixed in Mimir 3.1.7 and 3.2.2 and in GEM 2.17.20. GEM 2.11 through 2.16 will not receive a fix; users on those versions should upgrade to 2.17.20 or later.
Analysis and contextual insights are available on OpenCVE Cloud.
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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Mon, 02 Nov 2026 18:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Grafana Mimir's Alertmanager rejects tenant-supplied receiver configurations that reference local files, but the check did not cover two HTTP client settings: http_headers.<name>.files and basic_auth.username_file. A tenant permitted to upload an Alertmanager configuration could point these fields at any file readable by the Alertmanager process. When a notification was sent, Alertmanager read the file and put its contents in a header of the outgoing request. By directing the receiver at a server they control, the tenant could read files from the Alertmanager host, such as credentials and configuration. Exploitation requires permission to write the tenant's Alertmanager configuration. Grafana Enterprise Metrics (GEM), which is built on Mimir, is also affected. The issue is fixed in Mimir 3.1.7 and 3.2.2 and in GEM 2.17.20. GEM 2.11 through 2.16 will not receive a fix; users on those versions should upgrade to 2.17.20 or later. | |
| Title | Arbitrary file read via Alertmanager receiver configuration in Grafana Mimir | |
| Weaknesses | CWE-22 | |
| References |
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| Metrics |
cvssV3_1
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Subscriptions
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Status: PUBLISHED
Assigner: GRAFANA
Published:
Updated: 2026-11-02T19:06:58.641Z
Reserved: 2026-08-27T19:29:04.581Z
Link: CVE-2026-81938
No data.
Status : Awaiting Analysis
Published: 2026-11-02T19:18:11.127
Modified: 2026-11-02T19:34:23.993
Link: CVE-2026-81938
No data.
OpenCVE Enrichment
No data.
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CWE-22
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')